(a) Field of the invention
The present invention relates to an electrophoretic apparatus and, more particularly, to an electrophoretic apparatus for an automatic electrophoretic system to be used for analysis of blood serum proteins etc.
(b) Description of the prior art
For analysis of blood serum proteins in clinical study and the like, electrophoresis is usually adopted. To analyze blood serum proteins by electrophoresis, blood serum is applied onto a film made of cellulose acetate paper or the like (hereinafter referred to as film) and is subjected to electrophoresis in an electrophoretic apparatus. However, such processes required for analysis are carried out by handwork. Therefore, it is impossible to carry out the analysis efficiently. Moreover, to analyze many specimens of blood serum, it takes an extremely long time.
To eliminate the above-mentioned disadvantages of known electrophoresis, an automatic system is developed by automatizing all processes required for electrophoresis and arranging to perform all of those processes continuously. In the above-mentioned system, the electrophoretic apparatus in which the specimens are actually subjected to electrophoresis is arranged as follows. That is, a film onto which the blood serum specimens are applied is fed into the electrophoretic apparatus by means of a pair of endless belts arranged in the electrophoretic apparatus, stopped at a pre-determined position for the purpose of energizing the film and, then energized for a pre-determined time by keeping it stopped. After being energized, the film is transferred to the next process by starting the belts again. Now, detailed construction of the above-mentioned electrophoretic apparatus is described below referring to FIGS. 1 through 3. In these figures, numeral 1 designates a main body of electrophoretic apparatus, numeral 2 designates a lid and numeral 3 designates two pairs of rollers out of which one pair are arranged near an entrance 1a through which the film is fed into the main body 1 and the other pair are arranged near an exit 1b through which the film goes out of the main body 1 after electrophoresis. Numeral 4 designates a pair of endless belts applied to the rollers 3. Numeral 5 designates a motor which rotates the rollers 3 and thereby drives the endless belts 4. Therefore, when the film is inserted through the entrance 1a, the film is fed into the main body 1 by the belts 4 and, after being energized by the means to be described later, it is delivered out of the main body 1 through the exit 1b also by the belts 4. Numeral 6 designates a pair of partition walls fixed to the main body 1 or formed integrally with the main body 1. In trough portions 1c and 1d partitioned by the partition walls 6, buffer solution 7 is to be filled. Numeral 8 designates a pair of long board-like filter paper supports arranged on the right and left. Top surfaces of filter paper supports 8 are sloped as it is evident from their sections shown in FIG. 2. Numeral 10 designates a pair of supporting arms. At both ends of each supporting arm 10, leaf springs 11 are fixed and hold screws 9 which are respectively fixed to the filter paper supports 8. Thus, the filter paper supports 8 are dismountably supported. Numeral 12 designates a pair of supporting rods which support the supporting arms 10 and are mounted to the main body 1 so that the supporting rods 12 can be moved in vertical direction. Numeral 13 designates a pair of cams fixed to a shaft 14 and positioned just below the supporting rods 12. By roration of cams 13, the supporting rods 12 are moved upward and downward and the filter paper supports 8 are thereby moved upward and downward. Numeral 15 designates two sheets of filter paper. Each sheet of filter paper 15 is arranged that its one edge portion rests on the top surface of one of filter paper supports 8 and the other edge portion is dipped into buffer solution 7. Numeral 16 designates a pair of long board-like filter paper retainers respectively arranged above the filter paper supports 8. By inserting pins 16a fixed to each filter paper retainer 16 into slots 1e which are formed in the main body 1, each filter paper retainer 16 is held at a pre-determined height shown in FIG. 2. Numeral 17 designates a pair of wires stretched above the belts 4 by means of fixtures 18 fixed to the filter paper supports 8. Numeral 19 designates doors which are slidable in vertical direction for the purpose of opening and closing the entrance 1a and exit 1b. Numeral 20 designates crank mechanisms for moving the doors 19 upward and downward being operated by rotation of shaft 14.
Now, operation of the above-mentioned known electrophoretic apparatus is briefly described below. At first, the film to which blood serum specimens are applied is inserted through the entrance 1a by a suitable means. When the motor 5 is started at the same time in order to drive the endless belts 4, the film is fed into the main body 1 by the endless belts 4. When the film comes to a pre-determined position, the endless belts are stopped and, then, the shaft 14 are rotated by a suitable drive mechanism. Thus, the cams 13 fixed to the shaft 14 are rotated, the filter paper supports 8 are pushed up as explained before and the top surfaces of filter paper supports are pushed against the bottom surfaces of filter paper retainers 16. When, as shown in FIG. 2, it is so arranged that the distance between both endless belts 4 is smaller than the width of film 30 to which the blood serum specimens are applied, both edges of film 30 which is brought to the predetermined position on the endless belts 4 are projecting to the outside of endless belts 4. Therefore, when the filter paper supports are moved upward as described in the above, the film 30 also moves upward at the same time parting from the top surfaces of belts and is held between the filter paper supports 8 and filter paper retainers 16 together with the two sheets of filter paper 15. When the electrodes which are arranged in the buffer solution 7 but not illustrated are energized in the above state, the film 30 is energized through the two sheets of filter paper 15 for which one edge of each filter paper is dipped in the buffer solution 7.
On the other hand, when the shaft 14 is rotated, the doors 19 are moved upward through the crank mechanisms 20. Therefore, the entrance 1a and exit 1b are closed at the same time as the filter paper supports 8 are moved upward by rotation of cams 13 as described before. When the cams 13 are rotated and crank mechanisms are operated again after energizing for a pre-determined time, the filter paper supports 8 and doors 19 move downward. When the filter paper supports 8 move downward at that time, the wires 17 stretched across the fixtures 18, which are fixed to the filter paper supports 8, also move downward. Therefore, even if the film sticks to the filter paper retainers 16, it is moved downward without fail by means of the wires.
The film which is subjected to electrophoresis is thus placed on the endless belts 4 again. When the belts are driven by starting the motor at that time, the film is delivered to the outside through the exis 1b and is transferred to the next process.
The known electrophoretic apparatus described in the above has the following disadvantages. That is, when the film is conveyed to the pre-determined position for energization in the electrophoretic apparatus by means of endless belts, the middle portion of film which locates between the belts hangs slack and the film is energized in that state. Therefore, it is not possible to obtain favourable fractionated patterns. Moreover, as the filter paper retainers 16 have flat board-like shape, poor contact occurs between the film and filter paper when the edges of film are held between the filter paper supports 8 and filter paper retainers 16 unless it is so arranged that the respective contacting surfaces of filter paper supports 8 and filter paper retainers 16 have very favourable flatness so that there remains no such portion where those surfaces do not satisfactorily contact each other. Besides, when the filter paper supports 8 are moved downward in order to return the film onto the endless belts after energization, the film sometimes sticks to the filter paper retainers 16 and does not comes down onto the belts. In the known apparatus, it is therefore necessary to stretch the wires 17 and to separate the film from the filter paper retainers 16 by those wires when the filter paper supports 8 move downward. As, however, it is impossible to make the distance between the belts 4 and wires 17 large, the film sometimes gets jammed between the belts and wires when it is being conveyed by the belts.